Photonic devices comprising thermo-optic polymer

1. An integrated photonic device configured to be suitable for use as an optical component in a fiber-optic communications network that transmits optical signals having optical frequencies, said integrated photonic device comprising a single mechanical substrate supporting multiple coplanar regions of optical thin film assemblies upon the surface of said substrate, wherein: at least one of said multiple regions is a low-loss region comprising optical core and cladding materials configured to include at least one optical channel waveguide having a core and a cladding, wherein all of said core and cladding materials forming said low-loss region comprise inorganic optical compounds exhibiting low optical loss at the optical frequencies of the optical signals transmitted through the integrated photonic device, such as would be selected from a group of compounds including silica and doped-silica; and at least one other of said multiple regions is an active region comprising optical core and cladding materials configured to form an optical channel waveguide, wherein at least one of said core or cladding materials in said active region comprises at least in part at least one active optical compound that exhibits with respect to the inorganic optical compounds a substantially greater difference either or both in thermal conductivity and in change-of-refractive index in response to a stimulus, such as could be selected from a group of compounds including thermo-optic polymers, furthermore; said active region being physically adjacent to said low-loss region and said optical waveguide of said active region being optically aligned to the waveguide in said adjacent low-loss region.

2. An integrated photonic device according to claim 1 wherein the optical core of said active region comprises plural short segments of said active optical compound, each of said segments individually interposing through all or part of the waveguide core and/or all or part of the immediately adjacent waveguide cladding.

3. An integrated photonic device according to claim 1 wherein the waveguide of said active region has an optical axis and wherein the optical core of said waveguide of said active region has a trench along the optical axis such that disposed to each side of said trench along the axis there is a narrow rib of low-loss inorganic optical core material and within said trench there is the active optical compound, all configured such that the two ribs of this optical core provide axial guiding of an optical mode that spans said trench under conditions including those that provide the active material with an index-of-refraction lower than the index-of-refraction of the inorganic core material.

4. The integrated photonic device of claim 1 or claim 2 further comprising a source of said stimulus placed sufficiently closely to the active compound that said source of stimulus effects changes in the local distribution of refractive indices for the core and/or cladding materials in the vicinity of said source of stimulus.

5. The integrated photonic device of claim 4 wherein the active compound is thermo-optic and the source of stimulus is an electrically driven source of heat.

6. The integrated photonic device of claim 4 wherein the device comprises an interferometer having at least two arms and wherein at least one of the arms is comprised of at least one of the active regions.

7. The integrated photonic device of claim 4 wherein said device comprises at least two optically-coupled waveguides and a region containing active compound along at least part of the length over which the waveguides are optically coupled.

8. The integrated photonic device of claim 4 wherein said active region contains a digital optical switch made from an adiabatic Y-branch, an adiabatic X-branch, or a parabolic coupler and utilizing index gradients across the vicinity of the branching regions to enable switching functionality, said index gradients typically being about 10.sup.-4 per micron or greater.

9. The integrated photonic device of claim 4 wherein said device comprises an apparent waveguide intersection or junction of two waveguide channels wherein a bar of said active compound is positioned along the intersection or junction, the waveguides being positioned to the bar at about the critical angle to form a switch or modulator utilizing total-intemal-reflection of the guided optical signal along the bar.

10. The integrated photonic device of claim 1 wherein within at least one active region, the channel waveguide core is either the low-loss inorganic compound or the active compound and at least one of the adjacent claddings is the other of the low-loss inorganic compound and the active compound, and furthermore wherein the refractive index of the active compound is such that it is equal to the refractive index of the inorganic low-loss compound in response to the stimulus, such that when said index-equality is established the channel loses the ability to perform optical waveguiding.

11. The integrated photonic device of claim 1 or claim 2 wherein said device comprises at least one optical element having an optical path wherein said at least one active region is positioned in or along the optical path of said optical element and is configured to either enhance or suppress the response of the device to the stimulus and said device is selected from the group consisting of: a modulator; a variable optical attenuator; an M.times.N optical switch wherein M and N individually and independently have integer values greater than or equal to one; an arrayed-waveguide grating in which at least one said active region is placed along the waveguide array; a grating-based filter; and a Fabry-Perot filter having a resonator cavity in which the active compound is positioned within the resonator cavity, wherein the active compound is selected from the group consisting of: a thermo-optic polymer that changes refractive index in response to a heat stimulus; an electro-optic polymer that changes refractive index in response to an electric-field stimulus; a photo-elastic material that changes refractive index in response to a strain stimulus; a piezo-optic material that changes refractive index in response to a strain stimulus; and a photo-refractive material that changes refractive index in response to an optical-field stimulus.

12. The integrated photonic device of claim 3 wherein the two ribs and the active optical compound within said trench of said waveguide are configured with a geometry such that an optical signal of said optical signals traveling along said axis through said waveguide has only one guided optical mode for one or both of the transverse-electric and transverse-magnetic optical polarizations.

13. The integrated photonic device of claim 2 providing for a quasi-mode of the optical field, wherein said active segments individually have a first length and the portions of the core between adjacent active segments have a second length, and wherein the ratio of said first length to said second length is such that the thermal variation of propagation constant for said quasi-mode is substantially less in magnitude than for an optical signal solely in said active material or solely in said inorganic optical compounds, and said variation is essentially zero at a selected nominal operating temperature.

14. The integrated photonic device of claim 1 wherein the waveguide core is comprised of silica, said core has an overcoat of silica cladding having a thickness selected from a range from zero to about three microns, said silica cladding having a coating of active material having a thermo-optic coefficient of index substantially higher than that of said silica cladding such that the thermal variation of propagation constant for the primary mode of said waveguide is substantially less in magnitude than that of said silica cladding, and said variation being essentially zero at a selected nominal operating temperature.

15. A method of making an integrated photonic device, said method comprising the acts of: a) forming a plurality of inorganic waveguides on a single substrate using inorganic dielectric materials having low loss; and b) forming at least one active waveguide on said substrate wherein at least a portion of said device is formed of an active material having higher loss; c) wherein the majority of the waveguides formed on said substrate comprise said inorganic dielectric materials.

16. The method of claim 15 wherein said inorganic waveguides and said at least one active waveguide are optically interconnected so that an optical signal traveling through said active waveguide also travels through said passive waveguide.

17. The method of claim 16 wherein said inorganic waveguides and said at least one active waveguide are configured on said substrate to form at least one optical device having an active region.

18. The method of claim 16 wherein said inorganic waveguides and said at least one active waveguide are configured on said substrate to form and optically interconnect at least one optical device having an active region and at least one passive optical device having no active region.

19. The method of claim 18 wherein said active region is formed by placing a temporary filler in a region on said substrate where said active region is to be formed, and subsequently removing said temporary filler to create a void and filling said void with said active material.

20. The method of claim 15 wherein the act of forming at least one active waveguide on said substrate comprises removing at least a portion of at least one of said inorganic waveguides and replacing said portion with at least one active material to form said active waveguide.